JP2631750B2 - Covered arc welding rod for stainless steel - Google Patents

Description

The present invention relates to a coated arc welding rod for stainless steel, and more particularly, to welding of austenitic stainless steel,
Particularly, the present invention relates to a covered arc welding rod having good welding workability in a vertical position.

[Conventional technology]

Stainless steel is excellent not only in corrosion resistance and heat resistance, but also in workability and low-temperature and high-temperature mechanical properties. In recent years, new types of steel have been developed one after another with the expansion of applications.

[Problems to be solved by the invention]

However, when welding was performed, there were problems that were difficult to solve due to deterioration of the vertical bead shape due to the low thermal conductivity and high electrical resistance that are the characteristics of stainless steel, burning of the covered arc welding rod, etc. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a coated arc welding rod which has a good vertical bead shape and a good bar burn in coated arc welding of austenitic stainless steel, and which can secure various characteristics similar to those of a base material. I do.

[Means for Solving the Problems] The present inventors use a stainless steel core wire particularly among the coated arc welding rods for austenitic stainless steel in which the above-mentioned problems are most remarkable, and furthermore, use a lime titania-based wire. As a result of earnestly studying the solution for a welding rod containing a large amount of metal powder by adding Ni, Cr, Mo, and Cu as alloying agents to the coating agent, the following findings were found.

That is, by combining titanium carbonate such as rutile, which is a main component in the coating agent, and calcium carbonate in addition to calcium carbonate in an appropriate amount range, the stability of the arc in the standing posture and the fluidity of the slag are good. In this case, the vertical bead shape is smoothed and improved to some extent.

However, such means alone is not sufficient, so that the direction of arc spraying, which is determined by the uniformity of the arc spraying strength and the molten coating agent, which are factors necessary for further improving the vertical bead shape, is to be optimized. There is a need. For example, if the spraying of the arc is too strong, the base metal will be melted more than necessary at the time of welding, and as a result, the solidification of the molten metal will lag behind,
Become a convex bead. In addition, the direction of arc spraying depends on the uniformity of the molten coating agent as described above. To improve the uniformity of the molten coating agent, it is necessary to apply the coating agent uniformly around the core wire. Of course, even a coated welding rod with no eccentricity is affected by the heat of the molten metal or molten slag. The attachment direction is lower than the intended position, and as a result, the molten metal tends to hang down and become a convex bead shape.

In order to improve the uniformity of such a molten coating agent, it is effective to enhance the heat resistance of the coating agent. According to the study results of the present inventors, the method of reducing the content of the metal fluoride is the best result. I got However, when the content of the metal fluoride is excessively reduced, the arc becomes too weak, the stability of the arc is deteriorated, and defects such as poor fusion are likely to occur. As to the properties of such metal fluorides, although common tendency peculiar to metal fluorides was recognized, it was found that there was a difference in size depending on the type.

That is, by combining zircon potassium fluoride and magnesium fluoride in an appropriate amount range, it is possible to obtain a good arc spraying state that cannot be obtained with other fluorides and a smooth bead shape without impairing the heat resistance of the coating agent. Was done.

The present invention has been made based on the above findings, and the gist of the present invention is that Ni, Cr, Mo, Cu
Metal components are added to each other, the total of which is 16-40% by weight of the coating agent, 25-50% of titanium oxide, 10-30% of calcium carbonate, 1-5% of magnesium carbonate, and fluoride. Zircon potash is 1-5%, magnesium fluoride is 0.
A coated arc welding rod for stainless steel characterized in that a coating agent containing 1 to 2.0% and substantially free of metal fluorides other than zircon potassium fluoride and magnesium fluoride is applied to a stainless steel core wire. is there.

[Action]

 Hereinafter, the present invention will be described together with its operation.

Generally, welding rods for stainless steel use a common metal core wire to obtain the same chemical composition as the applicable steel type,
Further, a small amount of an alloying agent is often supplementarily added from the coating agent. However, this method has disadvantages such as the need to prepare various types of core wires in order to cope with increasingly diversified stainless steel types, so use a stainless steel core wire that is as versatile as possible. In many cases, alloy components are adjusted from the agent.

The welding rod of the present invention, such as when using a stainless steel core wire having a composition different from such a base material, Ni, Cr, from the coating agent
Although Mo and Cu are added, these alloy components need to be used in combination mainly for the purpose of ensuring high corrosion resistance of the weld metal. However, excessive addition of Ni, Cr, Mo, and Cu adversely affects the heat resistance of the coating agent. Therefore, when the total amount of each exceeds 16%, the method according to the present invention is particularly necessary. If it exceeds 40% of the upper limit, the heat resistance of the coating material is deteriorated even when the method according to the present invention is used, resulting in burning.

Titanium oxide improves the encapsulation of the slag, and particularly improves the bead shape in a downward or horizontal fillet position. However, if it is less than 25%, the effect is insufficient, and if it exceeds 50%, the fluidity of the slag in a standing posture deteriorates. Here, the titanium oxide refers to an oxide of titanium contained in rutile, illuminite, potassium titanate, and the like.

Calcium carbonate slightly improves the flowability of vertical slag and is also effective in preventing burning of sticks. However, when overdose,
Limit to 10 to 30% as spatter increases.

When magnesium carbonate is added in an amount of 1% or more, the spraying strength of the arc increases. However, if it exceeds 5%, spatter increases, so the amount is limited to 1 to 5%.

Zircon fluoride is suitable for preventing welding defects such as poor fusion, because the arc spraying is appropriately strengthened without impairing the arc concentration. Such effects are remarkably exhibited when the addition amount is 1% or more, but when the addition amount exceeds 5%, the spraying of the arc becomes too strong, so that the effect is limited to 1 to 5%.

Addition of 0.1% or more of magnesium fluoride moderately strengthens the arc spraying and improves the flowability of the vertical slag. However, if it exceeds 2.0%, the arc spraying becomes too strong, resulting in a convex bead. .

 Therefore, it is limited to 0.1 to 2.0%.

Metal fluorides other than zircon potassium fluoride and magnesium fluoride include calcium fluoride, barium fluoride, and aluminum fluoride, all of which have a bad effect on arc spraying, bead shape, and bar burning. Can not be added to

The welding rod of the present invention contains FeO, SiO ₂ ,
Metal oxides such as Al ₂ O ₃ , CaO, MgO, K ₂ O, and Na ₂ O can be added to ensure good welding workability and productivity.

As described above, the coated arc welding rod for stainless steel according to the present invention is used as an alloying agent in a lime titania-based coating agent.
Even if metal powders of Ni, Cr, Mo, and Cu are contained in large amounts, respectively, titanium oxide, calcium carbonate, magnesium carbonate, zircon potassium fluoride, and magnesium fluoride are added in appropriate amounts, and zircon potassium fluoride and magnesium fluoride are added. It is clear that by applying a coating agent that does not substantially contain metal fluorides other than the above to the stainless steel core wire, good welding performance such as welding workability in a vertical position can be secured from all of these synergistic effects. is there.

Here, referring to the method of manufacturing the welding rod, a core wire and a powder of a blended and mixed coating agent are prepared, and the coating agent powder is mixed with water glass (single or composite solution of potassium silicate aqueous solution and sodium silicate aqueous solution). 200 ~ 450 ℃
And bake for about 1 hour.

Examples Examples of the present invention will be described below.

Table 1 shows the chemical components of the test core wire. Table 2 shows the composition of the coated arc welding rod by the combination of the test core wire and the coating agent. Table 3 shows the chemical components of the base materials used.

Table 4 shows the results of welding workability tests performed using the coated arc welding rods of Table 2 and the base metal of Table 3.

The welding conditions in the downward position were a welding current of 140 A (AC), an arc voltage of 22 to 26 V, and a welding speed of 20 to 25 cm / min. FIG. 1 shows the groove shape of the test base material 1. In addition, 2 is a backing money.

The welding conditions in the upright position were: welding current; 100 A (AC), arc voltage: 20 to 24 V, welding speed: 5 to 10 cm / min, and the groove shape was as shown in FIG. The thickness t was 12 mm, the groove angle θ was 60 °, and the root gap G was 6 mm. Table 2 and 4
The coated arc welding rod symbols No1 to 10 in the table are comparative examples,
1 to 19 are examples of the present invention.

As is clear from the results in Table 4, in each comparative example, the total amount of Ni1, Cr, Mo, and Cu exceeded 40%, and calcium carbonate was less than 10%.

No2 has less than 25% titanium oxide and 3 calcium carbonate
Since it exceeds 0%, the encapsulation of the downward slag is poor, and there are many spatters.

No. 3 has more than 50% of titanium oxide and less than 10% of calcium carbonate.

No. 4 has less than 1% of magnesium carbonate, less than 1% of zircon potassium fluoride, and less than 0.1% of magnesium fluoride, and is out of the lower limit of each, so that arc spraying is too weak.

In No. 5, since magnesium carbonate exceeds 5%, the amount of spatters generated is too large.

No6 has more than 5% zircon potassium fluoride,
There are many spatters.

No7 has more than 2% magnesium fluoride,
There are many spatters.

No. 8 to No. 10 contain metal fluorides other than zircon potash and magnesium fluoride, and the upright bead shape becomes convex.

On the other hand, the welding rods of Nos. 11 to 19, which are the examples of the present invention, all had good downward and vertical workability.

〔The invention's effect〕

As described above, the coated arc welding rod for stainless steel according to the present invention is particularly excellent in workability in a vertical position,
It can be expected to improve welding efficiency and quality in applications mainly for vertical welding, such as chimney stainless steel.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a groove shape of a test base material for a downward and upright workability test. 1 ... base material for test, 2 ... backing metal, θ ... groove angle, t ... plate thickness, G ... root gap.

Claims (1)

(57) [Claims] (1) A metal component of Ni, Cr, Mo, Cu is added to a coating agent, respectively, and the total is 16 to 40% by weight of the total coating agent, titanium oxide: 25 to 50%, calcium carbonate: 10-30%, magnesium carbonate: 1-5%, zircon potassium fluoride: 1-5%,
Magnesium fluoride: A coating for stainless steel, characterized in that a coating agent containing 0.1 to 2.0% and containing substantially no metal fluoride other than zircon potassium fluoride and magnesium fluoride is applied to a stainless steel core wire. Arc welding rod.